A “63 amp supply” is a rating for the whole electrical service entering a property — the ceiling set at its main fuse or main switch — not a circuit size for any single appliance. You meet the figure most often on three-phase services, where 63 A is a per-phase rating. And no charger needs “a 63 amp supply” as such: each charger needs its own circuit, sized for its own draw. Whether your service has to be in that class is decided by a load assessment of everything the service already carries.
Key Takeaways
- A 63 amp supply is the service’s ceiling — a whole-property, usually per-phase, rating — not a charger circuit.
- Every load in the property shares that ceiling; the charger enters the sum as a circuit sized at 125% of its draw.
- No charger “needs” a named supply class: the load assessment decides whether your service fits the charger’s circuit.
- Raising the rating is the network operator’s project — their equipment, their agreement.
Where the 63 Amp Figure Lives
The number turns up in four places, and they are not interchangeable — when a quote uses it, pin down which one is meant:
| Where it appears | What it describes | Whose number it is |
|---|---|---|
| The service head / main fuse | The supply’s rating where it enters the property, at the network operator’s equipment | The network operator’s (DNO or utility) — theirs to set and theirs to change |
| The main switch at the consumer unit | The rating marked on the switch that isolates the whole installation | Read from the label — visible, photographable, nothing to open |
| The supply agreement or bill | The service as the utility records it for your address | The utility’s record — the definitive version of the figure |
| A quote or a charger’s paperwork | An assumption or requirement asserted about the three above | Yours to question: which one, and who confirmed it? |
Everything Under the Ceiling Shares It
A supply rating is not reserved for the charger. Heating, cooking, water heating and every socket draw under the same ceiling, and the charger joins them as one more claim — a heavy one, because charging is a continuous load: under the NEC’s rule the circuit is sized at 125% of the charger’s current, so a 32 A charger is planned as a 40 A circuit, a 40 A charger as 50 A, and a 48 A charger as 60 A. On a three-phase service the picture is per phase: loads are spread across the three phases, balanced by the installer’s design. Our guide to what size charger your panel can support walks through the counting.
So Do You Need a 63 Amp Supply?
The honest answer: the question is settled by a load assessment, not by matching numbers — it counts your existing loads under the code’s allowances and leaves one of three outcomes:
- Your service carries the charger as it stands. The common result where existing loads are modest, or the charger is a smaller class.
- It fits with the charger’s setting, or with managed charging. A unit configured below its maximum, or controlled against the home’s total draw, fits under a ceiling its full-rate version would not.
- An upgrade conversation starts. If the service itself must grow, that is the network operator’s side of the meter — their equipment, agreement and timetable — and a separate project from fitting the charger. The sums behind the outcomes are the load calculation basics an electrician works through.
Chargers Ask for Circuits, Not Supply Classes
No EVDANCE listing asks for a named supply class: chargers are specified by the circuit they need. The EV-ACT5006T wall charger draws up to 48 A, so it asks for a 60 A breaker on its own circuit. The ACS1605PE portable asks for something different in kind: 16 A on each phase of a three-phase supply, for its 11 kW. Whether either fits is the assessment’s answer, measured against your service — 63 A class or otherwise — and your existing loads, not a label on the box.
Frequently Asked Questions
My installer says my supply is 63 A. Is that good or bad?
Neither — it is the ceiling your assessment is measured against. It becomes good or bad news only once your existing loads and the charger’s circuit are counted under it.
Can a 63 A supply run two chargers?
Sometimes — the assessment decides, including how the two loads spread across phases on a three-phase service. Settings and managed charging are the levers that make a shared ceiling work.
Who can raise my supply rating if it is too small?
Only the network operator or utility: the rating belongs to their equipment and your supply agreement. It is not an alteration your installer — or you — can make on your side of the meter.
Related Reading
- What Size EV Charger Can I Have at Home? Panel Capacity Explained
- Adding EV Chargers to a Building: Load Calculation Basics
- What Size Breaker Do I Need for an EV Charger?
